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 * Copyright (c) 1994, 2013, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
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package java.lang;

/**
 * The Boolean class wraps a value of the primitive type
 * {@code boolean} in an object. An object of type
 * {@code Boolean} contains a single field whose type is
 * {@code boolean}.
 * <p>
 * In addition, this class provides many methods for
 * converting a {@code boolean} to a {@code String} and a
 * {@code String} to a {@code boolean}, as well as other
 * constants and methods useful when dealing with a
 * {@code boolean}.
 *
 * @author Arthur van Hoff
 * @since JDK1.0
 */
public final class Boolean implements java.io.Serializable,
    Comparable<Boolean> {

  /**
   * The {@code Boolean} object corresponding to the primitive
   * value {@code true}.
   */
  public static final Boolean TRUE = new Boolean(true);

  /**
   * The {@code Boolean} object corresponding to the primitive
   * value {@code false}.
   */
  public static final Boolean FALSE = new Boolean(false);

  /**
   * The Class object representing the primitive type boolean.
   *
   * @since JDK1.1
   */
  @SuppressWarnings("unchecked")
  public static final Class<Boolean> TYPE = (Class<Boolean>) Class.getPrimitiveClass("boolean");

  /**
   * The value of the Boolean.
   *
   * @serial
   */
  private final boolean value;

  /**
   * use serialVersionUID from JDK 1.0.2 for interoperability
   */
  private static final long serialVersionUID = -3665804199014368530L;

  /**
   * Allocates a {@code Boolean} object representing the
   * {@code value} argument.
   *
   * <p><b>Note: It is rarely appropriate to use this constructor.
   * Unless a <i>new</i> instance is required, the static factory
   * {@link #valueOf(boolean)} is generally a better choice. It is
   * likely to yield significantly better space and time performance.</b>
   *
   * @param value the value of the {@code Boolean}.
   */
  public Boolean(boolean value) {
    this.value = value;
  }

  /**
   * Allocates a {@code Boolean} object representing the value
   * {@code true} if the string argument is not {@code null}
   * and is equal, ignoring case, to the string {@code "true"}.
   * Otherwise, allocate a {@code Boolean} object representing the
   * value {@code false}. Examples:<p>
   * {@code new Boolean("True")} produces a {@code Boolean} object
   * that represents {@code true}.<br>
   * {@code new Boolean("yes")} produces a {@code Boolean} object
   * that represents {@code false}.
   *
   * @param s the string to be converted to a {@code Boolean}.
   */
  public Boolean(String s) {
    this(parseBoolean(s));
  }

  /**
   * Parses the string argument as a boolean.  The {@code boolean}
   * returned represents the value {@code true} if the string argument
   * is not {@code null} and is equal, ignoring case, to the string
   * {@code "true"}. <p>
   * Example: {@code Boolean.parseBoolean("True")} returns {@code true}.<br>
   * Example: {@code Boolean.parseBoolean("yes")} returns {@code false}.
   *
   * @param s the {@code String} containing the boolean representation to be parsed
   * @return the boolean represented by the string argument
   * @since 1.5
   */
  public static boolean parseBoolean(String s) {
    return ((s != null) && s.equalsIgnoreCase("true"));
  }

  /**
   * Returns the value of this {@code Boolean} object as a boolean
   * primitive.
   *
   * @return the primitive {@code boolean} value of this object.
   */
  public boolean booleanValue() {
    return value;
  }

  /**
   * Returns a {@code Boolean} instance representing the specified
   * {@code boolean} value.  If the specified {@code boolean} value
   * is {@code true}, this method returns {@code Boolean.TRUE};
   * if it is {@code false}, this method returns {@code Boolean.FALSE}.
   * If a new {@code Boolean} instance is not required, this method
   * should generally be used in preference to the constructor
   * {@link #Boolean(boolean)}, as this method is likely to yield
   * significantly better space and time performance.
   *
   * @param b a boolean value.
   * @return a {@code Boolean} instance representing {@code b}.
   * @since 1.4
   */
  public static Boolean valueOf(boolean b) {
    return (b ? TRUE : FALSE);
  }

  /**
   * Returns a {@code Boolean} with a value represented by the
   * specified string.  The {@code Boolean} returned represents a
   * true value if the string argument is not {@code null}
   * and is equal, ignoring case, to the string {@code "true"}.
   *
   * @param s a string.
   * @return the {@code Boolean} value represented by the string.
   */
  public static Boolean valueOf(String s) {
    return parseBoolean(s) ? TRUE : FALSE;
  }

  /**
   * Returns a {@code String} object representing the specified
   * boolean.  If the specified boolean is {@code true}, then
   * the string {@code "true"} will be returned, otherwise the
   * string {@code "false"} will be returned.
   *
   * @param b the boolean to be converted
   * @return the string representation of the specified {@code boolean}
   * @since 1.4
   */
  public static String toString(boolean b) {
    return b ? "true" : "false";
  }

  /**
   * Returns a {@code String} object representing this Boolean's
   * value.  If this object represents the value {@code true},
   * a string equal to {@code "true"} is returned. Otherwise, a
   * string equal to {@code "false"} is returned.
   *
   * @return a string representation of this object.
   */
  public String toString() {
    return value ? "true" : "false";
  }

  /**
   * Returns a hash code for this {@code Boolean} object.
   *
   * @return the integer {@code 1231} if this object represents {@code true}; returns the integer
   * {@code 1237} if this object represents {@code false}.
   */
  @Override
  public int hashCode() {
    return Boolean.hashCode(value);
  }

  /**
   * Returns a hash code for a {@code boolean} value; compatible with
   * {@code Boolean.hashCode()}.
   *
   * @param value the value to hash
   * @return a hash code value for a {@code boolean} value.
   * @since 1.8
   */
  public static int hashCode(boolean value) {
    return value ? 1231 : 1237;
  }

  /**
   * Returns {@code true} if and only if the argument is not
   * {@code null} and is a {@code Boolean} object that
   * represents the same {@code boolean} value as this object.
   *
   * @param obj the object to compare with.
   * @return {@code true} if the Boolean objects represent the same value; {@code false} otherwise.
   */
  public boolean equals(Object obj) {
    if (obj instanceof Boolean) {
      return value == ((Boolean) obj).booleanValue();
    }
    return false;
  }

  /**
   * Returns {@code true} if and only if the system property
   * named by the argument exists and is equal to the string
   * {@code "true"}. (Beginning with version 1.0.2 of the
   * Java<small><sup>TM</sup></small> platform, the test of
   * this string is case insensitive.) A system property is accessible
   * through {@code getProperty}, a method defined by the
   * {@code System} class.
   * <p>
   * If there is no property with the specified name, or if the specified
   * name is empty or null, then {@code false} is returned.
   *
   * @param name the system property name.
   * @return the {@code boolean} value of the system property.
   * @throws SecurityException for the same reasons as {@link System#getProperty(String)
   * System.getProperty}
   * @see java.lang.System#getProperty(java.lang.String)
   * @see java.lang.System#getProperty(java.lang.String, java.lang.String)
   */
  public static boolean getBoolean(String name) {
    boolean result = false;
    try {
      result = parseBoolean(System.getProperty(name));
    } catch (IllegalArgumentException | NullPointerException e) {
    }
    return result;
  }

  /**
   * Compares this {@code Boolean} instance with another.
   *
   * @param b the {@code Boolean} instance to be compared
   * @return zero if this object represents the same boolean value as the argument; a positive value
   * if this object represents true and the argument represents false; and a negative value if this
   * object represents false and the argument represents true
   * @throws NullPointerException if the argument is {@code null}
   * @see Comparable
   * @since 1.5
   */
  public int compareTo(Boolean b) {
    return compare(this.value, b.value);
  }

  /**
   * Compares two {@code boolean} values.
   * The value returned is identical to what would be returned by:
   * <pre>
   *    Boolean.valueOf(x).compareTo(Boolean.valueOf(y))
   * </pre>
   *
   * @param x the first {@code boolean} to compare
   * @param y the second {@code boolean} to compare
   * @return the value {@code 0} if {@code x == y}; a value less than {@code 0} if {@code !x && y};
   * and a value greater than {@code 0} if {@code x && !y}
   * @since 1.7
   */
  public static int compare(boolean x, boolean y) {
    return (x == y) ? 0 : (x ? 1 : -1);
  }

  /**
   * Returns the result of applying the logical AND operator to the
   * specified {@code boolean} operands.
   *
   * @param a the first operand
   * @param b the second operand
   * @return the logical AND of {@code a} and {@code b}
   * @see java.util.function.BinaryOperator
   * @since 1.8
   */
  public static boolean logicalAnd(boolean a, boolean b) {
    return a && b;
  }

  /**
   * Returns the result of applying the logical OR operator to the
   * specified {@code boolean} operands.
   *
   * @param a the first operand
   * @param b the second operand
   * @return the logical OR of {@code a} and {@code b}
   * @see java.util.function.BinaryOperator
   * @since 1.8
   */
  public static boolean logicalOr(boolean a, boolean b) {
    return a || b;
  }

  /**
   * Returns the result of applying the logical XOR operator to the
   * specified {@code boolean} operands.
   *
   * @param a the first operand
   * @param b the second operand
   * @return the logical XOR of {@code a} and {@code b}
   * @see java.util.function.BinaryOperator
   * @since 1.8
   */
  public static boolean logicalXor(boolean a, boolean b) {
    return a ^ b;
  }
}
